An electromagnetic contactor will be described by FIG. 19. FIG. 19 is a sectional view showing a configuration of the electromagnetic contactor. In FIG. 19, an electromagnetic contactor 100 comprises a fixed part and a movable part, and in the fixed part, a base 10 is coupled to a mount 23 by screws through a trip spring 30 compressed and mounted between a crossbar 2 and the mount 23. A primary fixed contact 25 having a contact 12 and an auxiliary fixed contact 26 are fixed in the base 10, and a fixed core 20 is held within the mount 23 through a rubber plate 22 for shock absorption, and an arc box 11 is provided on the base 10. An electromagnet forms a coil 21 by winding electric wires on a bobbin 24 and is positioned around a leg part of the fixed core 20.
In the movable part, a movable core 1 is joined to the crossbar 2 held within the base 10 by a pin 3, and a primary movable contact 4 is fitted in an upper window of the crossbar 2 through a press spring 5 and a contact spring 6, and a contact 7 opposite to the primary fixed contact 25 is provided in the primary movable contact 4. An auxiliary movable contact 8 opposite to the auxiliary fixed contact 26 is fitted in a center window of the crossbar 2 by an auxiliary contact spring 9.
The electromagnetic contactor 100 moves the movable core 1 from a first position to a second position with respect to the fixed core 20 by turning on or off excitation of the electromagnet, and in a state in which the electromagnet is not excited, a position of the movable core 1 in a state in which a wide gap between suction surfaces of the movable core 1 and the fixed core 20 is ensured is called a first position (it may be called a second position), and in a state in which the electromagnet is excited, a position of the movable core 1 in a state in which the movable core 1 moves with respect to the fixed core 2 to become a narrow gap (including a contact state of the gap with zero) between the suction surfaces is called a second position (it may be called a first position). The throwing of the electromagnetic contactor 100 means that the movable core 1 moves from the first position to the second position, and the opening of the electromagnetic contactor 100 means that the movable core 1 moves from the second position to the first position. Then, in the first position of the movable core 1, the top of the inverted T-shaped crossbar 2 is contacted and pressed to the base 10 by the trip spring 30 and so on.
Next, an operation of the electromagnetic contactor 100 configured as mentioned above will be described by FIG. 19. When a voltage is thrown to the coil 21 and a current flows, the fixed core 20 is magnetized and electromagnetic attraction force occurs in a gap g between the fixed core 20 and the movable core 1, and the movable core 1 is attracted to the fixed core 20 against the trip spring 30 and the contact springs 6, 9 by the attraction force and moves from the first position to the second position and also, the contact 7 of the movable contact 4 contacts and presses to the contact 12 of the fixed contact 25.
On the other hand, when the current of the coil 21 is broken, the fixed core 20 is demagnetized, so that the movable core 1 is released from suction and moves from the second position to the first position and also, the contact 7 and the contact 12 are opened.
However, in the configuration of the above-mentioned electromagnetic contactor 100, by the throwing or breaking of the current of the coil 21, the movable core 1 has a high collision speed to the fixed core 2 and repeats bounce operations for a while. Due to vibration associated with such a repeat, so-called chattering in which the contact 7 of the primary movable contact 4 and the contact 12 of the primary fixed contact 25 connect or disconnect for a short time is generated.
Therefore, there were problems that a large shock sound occurs from the movable core 1, the fixed core 20, the crossbar 2, the base 10, etc. by the above-mentioned throwing or breaking and dust occurs from the movable core 1 etc. or repeat shocks are applied to the crossbar 2, the base 10 and so on.